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Actively exploited in the wild. This CVE is on the CISA Known Exploited Vulnerabilities list — treat remediation as urgent. Federal remediation due by 17 Nov 2021. Known ransomware use
Confluence Data CenterApplication · Atlassian

CVE-2021-26084

CRITICAL · 9.8 CVSS v3.1 Published 2021-08-30
Fix available
A fix is available. Upgrade to 6.13.23 / 7.4.11 or later.
See remediation →
100/100
Remediation priority · Urgent
In the wild Ransomware High EPSS Public exploit Remotely reachable No privileges Zero-click Patch available

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
In affected versions of Confluence Server and Data Center, an OGNL injection vulnerability exists that would allow an unauthenticated attacker to execute arbitrary code on a Confluence Server or Data Center instance. The affected versions are before version 6.13.23, from version 6.14.0 before 7.4.11, from version 7.5.0 before 7.11.6, and from version 7.12.0 before 7.12.5.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

OGNL injection vulnerability in Atlassian Confluence Server and Data Center allowing unauthenticated attackers to execute arbitrary code by injecting malicious OGNL expressions. The vulnerability affects multiple version ranges and has a CVSS score of 9.8 (Critical), indicating severe risk with network-exploitable remote code execution capability.

MitigationImmediately upgrade Confluence to a patched version (6.13.23, 7.4.11, 7.11.6, or 7.12.5 or later) or apply available security patches, as this unauthenticated RCE vulnerability has known active exploitation in the wild.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Confluence Data CenterApplication
Affected:< 6.13.23>= 6.14.0, < 7.4.11>= 7.5.0, < 7.11.6>= 7.12.0, < 7.12.5
Confluence ServerApplication
Affected:< 6.13.23>= 6.14.0, < 7.4.11>= 7.5.0, < 7.11.6>= 7.12.0, < 7.12.5

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Locate installed Confluence version
    Log in as an administrator and navigate to the Confluence Administration console, or examine the confluence.cfg.xml configuration file typically located in the <confluence-home>/ directory. The version number is displayed in the 'About' section or stored as the 'confluence.version' property in the configuration file.
    Affected if The installed version falls within any of these ranges: < 6.13.23; >= 6.14.0 and < 7.4.11; >= 7.5.0 and < 7.11.6; >= 7.12.0 and < 7.12.5
  2. Confirm product type
    Determine whether the affected system is Atlassian Confluence Server or Atlassian Confluence Data Center. This information is visible in the Confluence Administration 'About' page or in the confluence.cfg.xml file under the 'confluence.edition' property.
    Affected if The product is Confluence Server or Confluence Data Center running a version that matches the affected ranges listed above.
  3. Verify web template handling is enabled
    Confluence web template handling is a core feature required for page rendering. By default, the /pages/ and /spaces/ endpoints that handle web templates are accessible to all users, including unauthenticated users in default configurations. Check the general configuration settings in Confluence Administration under Security and Global Permissions.
    Affected if Unauthenticated or low-privilege users can access Confluence pages and spaces, which enables the web template injection vector.
  4. Compare against known safe versions
    Identify whether the installed version matches one of the patched releases: 6.13.23, 7.4.11, 7.11.6, or 7.12.5 or later. Any version below these thresholds within the affected branches is considered vulnerable.
    Affected if The installed version is lower than the patched versions listed and falls into the affected version ranges.

A Confluence Server or Data Center instance is affected if it runs any version below 6.13.23, between 6.14.0 and 7.4.10, between 7.5.0 and 7.11.5, or between 7.12.0 and 7.12.4, with web template endpoints exposed to unauthenticated or low-privilege users.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 6.13.23 / 7.4.11 / 7.11.6 or later
Fixed in 6.13.237.4.117.11.6
Vendor patch jira.atlassian.com →
Interim mitigation

Immediately upgrade Confluence to a patched version (6.13.23, 7.4.11, 7.11.6, or 7.12.5 or later) or apply available security patches, as this unauthenticated RCE vulnerability has known active exploitation in the wild.

Recommended fix High confidence

Confluence Server/Data Center 7.12.5 or later (or 7.11.6, 7.4.11, or 6.13.23 depending on your current major version branch)

  1. 1. Take a complete backup of the Confluence database and home directory
  2. 2. Download the appropriate fixed version of Confluence Server or Data Center (7.12.5 or later recommended)
  3. 3. Stop the Confluence service
  4. 4. Install the upgraded Confluence version following Atlassian's upgrade documentation
  5. 5. Start the Confluence service
  6. 6. Verify the upgrade was successful by logging in and checking the version number
  7. 7. Test critical functionality to ensure the upgrade did not break existing workflows
Caveat Standard Confluence upgrade considerations apply - review Atlassian's upgrade guide for your version jump for any required pre-upgrade steps or compatibility notes

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Confluence Data Center Exploited in the wild — priority engagement
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing4.0 h
  • Review / QA2.0 h
12.0 hours of engineering $2,080
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An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,328.

Scan for this in your stack

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2021-26084 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data